Smaller pulley for P600B
Thread Starter
Drifting
Joined: Dec 2003
Posts: 1,564
Likes: 28
From: Medina OH
Smaller pulley for P600B
Oh gurus of P600B's :steering: I'm considering going with a smaller pulley to increase boost. Have any of you done this? Any recommendations? Most importantly, if you have reduced your pulley size -- where did you get it (how much?)? :flag
Race Director
Joined: Feb 2002
Posts: 11,268
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From: Honolulu, HI
Re: Smaller pulley for P600B (85 Stalker)
You have to be careful not to overspin your blower. You have to determine what diameter your pulley is and what your crank pulley diameter is. From there, use the forumla for determining the Max Blower RPM at max engine RPM.
This is something I have to figure out too for my new pulley. Go to http://www.procharger.com to find the forumla or give them a call.
This is something I have to figure out too for my new pulley. Go to http://www.procharger.com to find the forumla or give them a call.
Melting Slicks
Joined: May 2000
Posts: 2,148
Likes: 1
From: Chandler AZ
Re: Smaller pulley for P600B (vvv90)
Don't worry about it- you can't overspin a P600B even with the smallest pulley they sell.
With a 7" crank, 2.25" blower pulley, plus 3.05 internal step-up, you get 57K rpm at the impeller at 6000 rpm engine.
You'll hit the limit of 60K impeller at around 6300rpm; but unless you're running a solid roller with a miniram or something you won't be operating up there.
With a 7" crank, 2.25" blower pulley, plus 3.05 internal step-up, you get 57K rpm at the impeller at 6000 rpm engine.
You'll hit the limit of 60K impeller at around 6300rpm; but unless you're running a solid roller with a miniram or something you won't be operating up there.
Safety Car
Joined: Apr 2001
Posts: 3,525
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From: Houston TX
Re: Smaller pulley for P600B (gcrouse)
gcrouse is correct in that you can not overspin your P-600B with a long tube intake motor.
I have run almost every size pulley available back when I ran a P-600B on another combination, and found that the boost available from the 2.4" and the 2.25" pulley were nearly identical due to the fact that the 2.25" pulley displayed much more "slippage than the 2.4". I had the relocated idler, and still had problems with the smaller pulley.
With stock heads and a small cam, and the 2.4" pulley, you should see boost in the 14.7+ range (assuming no belt slippage).
Aaron
I have run almost every size pulley available back when I ran a P-600B on another combination, and found that the boost available from the 2.4" and the 2.25" pulley were nearly identical due to the fact that the 2.25" pulley displayed much more "slippage than the 2.4". I had the relocated idler, and still had problems with the smaller pulley.
With stock heads and a small cam, and the 2.4" pulley, you should see boost in the 14.7+ range (assuming no belt slippage).
Aaron
Thread Starter
Drifting
Joined: Dec 2003
Posts: 1,564
Likes: 28
From: Medina OH
Re: Smaller pulley for P600B (AKS Racing)
Thanks guys -- I should have no problem with the 2.25 slipping. When I added a March 508 AC, we had to big time modify a Zoops correct align bracket. This setup has an adjustment rod, and we can make the belt VERY tight :rofl:
http://www.angelfire.com/theforce/corvette
With all the other mods on the 383 stroker engine, I believe the smaller pulley will be the ticket (and of course switching the March UD crank pulley back to the factory pulley) :sad: :sad: :sad: I'm going to call ATI in the morning and order a couple sizes. Do you recall what you paid for the pulleys???
[Modified by 85 Stalker, 4:51 PM 12/18/2003]
http://www.angelfire.com/theforce/corvette
With all the other mods on the 383 stroker engine, I believe the smaller pulley will be the ticket (and of course switching the March UD crank pulley back to the factory pulley) :sad: :sad: :sad: I'm going to call ATI in the morning and order a couple sizes. Do you recall what you paid for the pulleys???
[Modified by 85 Stalker, 4:51 PM 12/18/2003]
Race Director
Joined: Feb 2002
Posts: 11,268
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From: Honolulu, HI
Re: Smaller pulley for P600B (85 Stalker)
Guys, don't be so sure he can't overspin his blower, he said before that he was running March pulleys which might be smaller, That's why I told him to figure it with the proper formula.
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Safety Car
Joined: Apr 2001
Posts: 3,525
Likes: 2
From: Houston TX
Re: Smaller pulley for P600B (vvv90)
The March pulley set would only slow the blower down (i.e. crank pulley will be smaller, thus blower spins slower). I have yet to see anyone marketing larger pulleys for the corvette, as there are cradle interference issues at the bottom.
I will reiterate, you will not overspeed the P-600B with a long runner intake L-98. I will also reiterate, you WILL get slippage with the 2.25" blower pulley, because before you can tighten the belt enough to prevent slippage, you WILL destroy the bearings in both the water pump and the alternator. Think about it. Don't bother ordering the 2.25".
ATI charges $80/pulley, other vendors charge $40-50.
Aaron
I will reiterate, you will not overspeed the P-600B with a long runner intake L-98. I will also reiterate, you WILL get slippage with the 2.25" blower pulley, because before you can tighten the belt enough to prevent slippage, you WILL destroy the bearings in both the water pump and the alternator. Think about it. Don't bother ordering the 2.25".
ATI charges $80/pulley, other vendors charge $40-50.
Aaron
Thread Starter
Drifting
Joined: Dec 2003
Posts: 1,564
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From: Medina OH
Re: Smaller pulley for P600B (AKS Racing)
I think I'll go back to the basics first, and put the factory pulley back on to see what boost the new engine pulls. You were right about the brace -- we had to do quite a bit of work on it to clear the new balancer and pulley. We actually had to cut almost five inches out of it. Otherwise, the crank pulley sat right on the brace. Believe me, that was a nightmare!!!! :crazy:
Thread Starter
Drifting
Joined: Dec 2003
Posts: 1,564
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From: Medina OH
Re: Smaller pulley for P600B (krivera)
Thanks Krivera -- I feel like I put the car through college twice!!! Now that the engine is almost done, it is time to start on the interior. Last year during the Michgan Woodward Dream Cruise I had the ultimate thing happen. I was parked by an AWSOME Yellow Diablo, and more people were asking me about the Vette than the Diablo.... That was pretty cool!!!! Mostly because it ate at the guy with the $250Kcar:cheers:
Safety Car
Joined: Apr 2001
Posts: 3,525
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From: Houston TX
Re: Smaller pulley for P600B (85 Stalker)
Why would you have to cut anything out of the cradle? Even with the 14lb Fluidampner (really big one), you do not have to clearance the cradle under the harmonic balancer and crank pulley. You must have something wrong with the motor mounts, engine alignment, etc. Check all this prior to going any further.
The factory crank pulley will increase the boost, but you will also have to go back to the factory water pump pulley.
Also, what rpm were you measuring the boost. On one of my old combinations with SuperRam, large cam, big heads, and P-600B, the engine would pull 12 psi at 6100. Boost is very dependent upon RPM on the P600B due to the low step-up ratio.
Aaron
The factory crank pulley will increase the boost, but you will also have to go back to the factory water pump pulley.
Also, what rpm were you measuring the boost. On one of my old combinations with SuperRam, large cam, big heads, and P-600B, the engine would pull 12 psi at 6100. Boost is very dependent upon RPM on the P600B due to the low step-up ratio.
Aaron
Thread Starter
Drifting
Joined: Dec 2003
Posts: 1,564
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From: Medina OH
Re: Smaller pulley for P600B (AKS Racing)
Since we converted the 4+3 to a TCI Th350, we had to modify the mounts (trans and engine), and build a custom cross bar / trans brace. We also made a modular "cage" to connect the rear shaft to the torque tube.
This brought the engine "down" ~ 3/4 inches (?). I wish I knew how to post a photo, I would like to show you the modifications we made for the crank. What is the trick to post/attach photos?!?!?!?!
Under the hood, about the only stock item I have is the brake booster :D http://www.angelfire.com/theforce/corvette
This brought the engine "down" ~ 3/4 inches (?). I wish I knew how to post a photo, I would like to show you the modifications we made for the crank. What is the trick to post/attach photos?!?!?!?!
Under the hood, about the only stock item I have is the brake booster :D http://www.angelfire.com/theforce/corvette
Safety Car
Joined: Apr 2001
Posts: 3,525
Likes: 2
From: Houston TX
Re: Smaller pulley for P600B (85 Stalker)
I have run the older transmissions in the C4s. You are correct that you have to modify the tailshaft housing and the C beam ("ladder"), but you do not have to modify the engine mounts.
Now that you have explained this, I have some more bad news. To install the larger diameter crank pulley on an engine that sits 3/4" lower in the cradle will require more cutting on the cradle. Will be a bit tough, but can be done with the plasma arc in the car. Any thoughts on the integrity of the cradle following the "surgery". I really hate to cut on these cars unless absolutely necessary.
I really do not know what to advise, except to re-install the factory motor mounts. If you did that, then you are back to square one where you can re-install the original pulley and get boost.
BTW, you never advised as to what level of boost you are seeing and at what RPM.
Post pics using the image button, install photo location between the two brackets (
).
Aaron
Now that you have explained this, I have some more bad news. To install the larger diameter crank pulley on an engine that sits 3/4" lower in the cradle will require more cutting on the cradle. Will be a bit tough, but can be done with the plasma arc in the car. Any thoughts on the integrity of the cradle following the "surgery". I really hate to cut on these cars unless absolutely necessary.
I really do not know what to advise, except to re-install the factory motor mounts. If you did that, then you are back to square one where you can re-install the original pulley and get boost.
BTW, you never advised as to what level of boost you are seeing and at what RPM.
Post pics using the image button, install photo location between the two brackets (
Aaron
Race Director
Joined: Feb 2002
Posts: 11,268
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From: Honolulu, HI
Re: Smaller pulley for P600B (AKS Racing)
[whisper] ....get a D1-R instead :yesnod: [/whisper]
with all the money you've spend so far, what's another $2500.
[Modified by vvv90, 2:00 PM 12/19/2003]
with all the money you've spend so far, what's another $2500.
[Modified by vvv90, 2:00 PM 12/19/2003]
Thread Starter
Drifting
Joined: Dec 2003
Posts: 1,564
Likes: 28
From: Medina OH
Re: Smaller pulley for P600B (vvv90)
It kills me, I should have ordered the D1..... I just hate to do it now since I have a two year old (though still BRAND NEW!) P600B..... :sad: :sad: :sad:
The shop modified High Energy motor mounts for this application. Since HE does not make mounts for C4 Vettes :mad I still have the original mounts, which are in excellent shape -- we did talk about using them again. They would sit higher than the HE mounts.
The shop modified High Energy motor mounts for this application. Since HE does not make mounts for C4 Vettes :mad I still have the original mounts, which are in excellent shape -- we did talk about using them again. They would sit higher than the HE mounts.
Race Director
Joined: Feb 2002
Posts: 11,268
Likes: 14
From: Honolulu, HI
Re: Smaller pulley for P600B (85 Stalker)
It kills me, I should have ordered the D1..... I just hate to do it now since I have a two year old (though still BRAND NEW!) P600B..... :sad: :sad: :sad:
Race Director
Joined: Feb 2002
Posts: 11,268
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From: Honolulu, HI
Re: Smaller pulley for P600B (85 Stalker)
Thats definitely something you need to find out. Contact ATI. If you look at their website, the dimensions are identical. If I were you, I'd try to go with the D1-R. The dimensions are only slightly larger and the step up is the same, but it flows more and probably pushes more air at a lower RPM too.
http://www.procharger.com/models.shtml
[Modified by vvv90, 11:39 AM 12/20/2003]
http://www.procharger.com/models.shtml
[Modified by vvv90, 11:39 AM 12/20/2003]
Safety Car
Joined: Apr 2001
Posts: 3,525
Likes: 2
From: Houston TX
Re: Smaller pulley for P600B (85 Stalker)
The D1/D1R (7-8 mount points) does not mount to the same brackets as the P-600B (4 mount points) nor the P1/P1SC. However, the bracketry is simple enough to make, and if you make your own or buy one from one of the nice fellows on this forum, you can address some of the inherent shortcomings in ATIs brackets.
I have a factory ATI D series bracket laying around (never used from a system).
Aaron
I have a factory ATI D series bracket laying around (never used from a system).
Aaron